On Thu, Sep 20, 2012 at 10:11 AM, Nishanth Aravamudan
<[email protected]> wrote:
> Hi David,
>
> On 20.09.2012 [17:50:52 +0100], David Lee wrote:
>> Cobbler version: 2.0.11 (actually 2.0.11-2 from RPM)
>> All systems: RHEL 5.8
>>
>>
>> [Preliminary: I realise our cobbler version is a little old.  I'd
>> rather not have to upgrade right now, but if it really would make a
>> substantial difference to the problem I am about to describe, that
>> could be done.]
>>
>> We install RHEL 5.8 on many IBM boxes, which are all very similar.  In
>> particular there are four ethernet ports on the system itself, and a
>> separate board with two 10-Gig ports.
>>
>> The first ethernet port is our provisioning network, over which
>> cobbler runs.  During installation, it seems to call this "eth2".  But
>> after installation it almost always comes up as "eth0".  (That's OK
>> (although I don't understand it!) but it might interact slightly with
>> the real problem below.)  Moving on...
>>
>> After installation, the four system ethernet ports usually get
>> assigned names eth0, eth1, eth2 and eth3, usually in order. (The
>> cobbler/provisioning interface seems to get "eth0" always.)  The two
>> 10-Gig ports get assigned names eth4 and eth5... usually.
>>
>> But occasionally (perhaps 10% or slightly more) an installation ends
>> up with a different mapping of names to ports.  (If we then
>> re-install, it usually gets the expected mapping.)  That is a problem
>> when one is (re-)installing machines in a farm of machines that are
>> supposed to be the same.
>
> So a couple of questions spring to mind.
>
> 1) Is the naming somehow critical to your application? I assume so,
> because I'm not sure why it's relevant otherwise.
>
> 2) If you want static naming of interfaces, I believe the right way of
> doing this is custom udev rules (which you might install via cobbler).
>
> 3) I think the normal way for this to work is to always use the MAC
> address to identify the physical port.
>
>> I realise that "cobbler system" has a "--interface" capability.  But I
>> don't see a way for that to be used to map specific names to specific
>> hardware.
>>
>> I make no claims to understand the depths and intricacies of
>> "/etc/modprobe.conf", "/etc/sysconfig/hwconf", kudzu, etc.  But is
>> there a way (or common practice) somehow to pre-populate various
>> things with relevant information for the mapping of generated "eth*"
>> names onto particular ethernet ports?
>
> This isn't really a Cobbler specific question, afaict. I would look into
> udev rules, probably, if relevant.
>
> Thanks,
> Nish
>

This problem is solved when you move from ethX designation to the new
p32pX designations (keyed to bus locations) - I don't know if that is
available outside of Fedora yet. try yum info biosdevname - see
http://fedoraproject.org/wiki/Features/ConsistentNetworkDeviceNaming
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